Fluid machine

ABSTRACT

A fluid machine includes a housing, an electric motor, a drive circuit that includes a heat-generating component and drives the electric motor, a cover that defines an accommodation chamber, which accommodates the drive circuit, with the housing, and a fastener that fastens the cover to the housing. The cover is configured to press the heat-generating component or a heat transfer member, to which heat of the heat-generating component is transferred, against the housing in a fastening direction of the fastener when fastened by the fastener. The fluid machine further includes a seal that is held between the first opposing surface of the housing and the second opposing surface of the cover in the direction intersecting the fastening direction of the fastener.

TECHNICAL FIELD

The present invention relates to a fluid machine.

BACKGROUND ART

A known motor-driven compressor serving as a fluid machine includes an electric motor and a drive circuit that drives the electric motor (refer to, for example, Japanese Laid-Open Patent Publication No. 2003-324900). The drive circuit is coupled to a housing through which fluid is drawn. Heat is exchanged between the fluid and the drive circuit through the housing to cool the drive circuit.

SUMMARY OF THE INVENTION

A cover that accommodates the drive circuit may be fastened to the housing. When the drive circuit includes a heat-generating component, the heat of the heat-generating component is apt to collect in the cover. Thus, the cooling efficiency needs to be increased.

Further, when the cover is fastened to the housing, for example, a seal may be arranged between the housing and the cover so that foreign matter such as dust or water does not enter the drive circuit through a gap between the housing and the cover. When force resulting from the fastening is applied to the seal over a long time, the seal easily deteriorates. Deterioration of the seal may lower the seal performance.

It is an object of the present invention to provide a fluid machine that increases the efficiency for cooling a heat-generating component and limits deterioration of a seal.

A fluid machine that solves the above problem includes a housing including a suction port through which fluid is drawn, an electric motor accommodated in the housing, a drive circuit that includes a heat-generating component and drives the electric motor, a cover that is arranged on an outer surface of the housing and defines an accommodation chamber, which accommodates the drive circuit, with the housing, and a fastener that fastens the cover to the housing. The cover is configured to press the heat-generating component or a heat transfer member, to which heat of the heat-generating component is transferred, against the housing in a fastening direction of the fastener when fastened by the fastener. The housing includes a first opposing surface, and the cover includes a second opposing surface that opposes the first opposing surface in a direction intersecting the fastening direction of the fastener. The fluid machine further includes a seal arranged between the first opposing surface and the second opposing surface. The seal is held between the first opposing surface and the second opposing surface in the direction intersecting the fastening direction of the fastener.

Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view schematically showing a first embodiment of a motor-driven controller;

FIG. 2 is a cross-sectional view schematically showing an inverter circuit and the surrounding of the inverter circuit in the motor-driven compressor shown in FIG. 1;

FIG. 3 is a cross-sectional view schematically showing an inverter circuit and the surrounding of the inverter circuit in a second embodiment of a motor-driven compressor; and

FIG. 4 is a cross-sectional view schematically showing an inverter circuit and the surrounding of the inverter circuit in another example of a motor-driven compressor.

EMBODIMENTS OF THE INVENTION First Embodiment

A motor-driven compressor serving as a first embodiment of a fluid machine will now be described. The motor-driven compressor of the present embodiment is installed in a vehicle for use with an on-vehicle air conditioner.

As shown in FIG. 1, an on-vehicle air conditioner 200 includes a motor-driven compressor 10 serving as a fluid machine and an external refrigerant circuit 201 that supplies refrigerant, which serves as fluid, to the motor-driven compressor 10. The external refrigerant circuit 201 includes, for example, a heat exchanger and an expansion valve. When cooling or heating the passenger compartment, the on-vehicle air conditioner 200 uses the motor-driven compressor 10 to compress refrigerant and the external refrigerant circuit 201 to exchange heat with the refrigerant and expand the refrigerant.

The motor-driven compressor 10 includes a housing 11, a compression unit 12, and an electric motor 13. The housing 11 includes a suction port 11 a through which refrigerant is drawn from the external refrigerant circuit 201. The compression unit 12 and the electric motor 13 are accommodated in the housing 11.

The entire housing 11 is round and hollow (more specifically, substantially tubular). The housing 11 is formed from a thermally conductive material (for example, metal such as aluminum). The housing 11 includes a discharge port 11 b through which refrigerant is discharged. Refrigerant exists in the housing 11, and heat is exchanged between the housing 11 and the refrigerant. That is, the housing 11 is cooled by refrigerant. Further, the housing 11 is electrically connected to ground.

When a rotation shaft 21 (described later) rotates, the compression unit 12 compresses refrigerant drawn through the suction port 11 a into the housing 11 and discharges the compressed refrigerant through the discharge port 11 b. The compression unit 12 may be of any structure such as a scroll type, a piston type, or a vane type.

The electric motor 13 drives the compression unit 12. The electric motor 13 includes the rotation shaft 21 that is, for example, rotationally supported by the housing 11, a tubular rotor 22 fixed to the rotation shaft 21, and a stator 23 fixed to an inner circumferential surface of the housing 11. The axial direction of the rotation shaft 21 corresponds to the axial direction of the tubular housing 11 (hereinafter referred to as “axial direction Z”). The stator 23 includes a tubular stator core 24 and coils 25 that are wound around teeth of the stator core 24. The rotor 22 and the stator 23 are opposed to each other in the radial direction of the rotation shaft 21. When current is supplied to the coils 25, the rotor 22 and the rotation shaft 21 rotate so that the compression unit 12 compresses refrigerant.

The motor-driven compressor 10 includes an inverter circuit 30, a cover 40, and fasteners 50. The inverter circuit 30 serves as a drive circuit that drives the electric motor 13. The cover 40 is arranged on an outer surface of the housing 11 (i.e., outer surface 11 d of coupling wall 11 c) and defines an accommodation chamber S1, which accommodates the inverter circuit 30, with the housing 11. The fasteners 50 fasten the cover 40 to the housing 11.

The inverter circuit 30 converts direct current power of a power storage device or the like installed in a vehicle into alternating current power that drives the electric motor 13.

As shown in FIG. 2, the inverter circuit 30 includes, for example, a circuit board 31 and a heat-generating component 32 connected to the circuit board 31. The heat-generating component 32 includes terminals 32 a and is connected to the circuit board 31 by the terminals 32 a.

The heat-generating component 32 may be any component of the inverter circuit 30 that generates heat. For example, the heat-generating component 32 may be a power module including switching elements and a coil or a capacitor of a filter circuit that reduces noise included in direct current power input to the inverter circuit 30.

As shown in FIG. 1, the cover 40 is coupled to the outer surface 11 d of the coupling wall 11 c. The housing 11 includes two ends in the axial direction Z. The coupling wall 11 c is arranged at one of the two ends located at a side opposite to the discharge port 11 b. The compression unit 12, the electric motor 13, and the inverter circuit 30 are arranged in the axial direction Z. That is, the motor-driven compressor 10 is of an in-line type.

The cover 40 is formed from a thermally conductive material, for example, metal such as aluminum. As shown in FIG. 2, the entire cover 40 is tubular. The cover 40 includes a body 41 and a flange 46. The body 41 includes a bottom portion 42 (end wall), a side portion 43 (circumferential wall), and an opening 41 a that opens toward the housing 11 (i.e., coupling wall 11 c).

More specifically, the body 41 includes the bottom portion 42 and the side portion 43 that extends from an outer edge of the bottom portion 42 toward the coupling wall 11 c. In other words, the body 41 includes the side portion 43 (circumferential wall) including a first end and a second end located at a side opposite to the first end, the bottom portion 42 (end wall) located at the first end, and the opening 41 a located at the second end. The side portion 43 forms a step. The body 41 includes an inner surface 44. The inner surface 44 includes a first inner circumferential surface 44 a located at a side corresponding to the bottom portion 42 of the body 41 (side corresponding to first end), a second inner circumferential surface 44 b located at a side corresponding to the housing 11 (side corresponding to second end), and a coupling surface 44 c (step surface) that couples the first inner circumferential surface 44 a and the second inner circumferential surface 44 b. More specifically, the inner surface 44 includes the first inner circumferential surface 44 a that is continuous with an inner surface 42 a of the bottom portion 42 and extends from the inner surface 42 a of the bottom portion 42 toward the housing 11, the coupling surface 44 c that is continuous with the first inner circumferential surface 44 a, and the second inner circumferential surface 44 b that is continuous with the coupling surface 44 c and extends from the coupling surface 44 c toward the housing 11. The coupling surface 44 c is perpendicular to the first inner circumferential surface 44 a and the second inner circumferential surface 44 b.

A straight line L1 that extends through the center M (i.e., center M in radial direction) of the first inner circumferential surface 44 a and connects two points on the first inner circumferential surface 44 a is shorter than a straight line L2 that extends through the center M (i.e., center M in radial direction) of the second inner circumferential surface 44 b and connects two points on the second inner circumferential surface 44 b. In the present embodiment, the first inner circumferential surface 44 a and the second inner circumferential surface 44 b are circular as viewed in the axial direction Z, and the diameter (L2) of the second inner circumferential surface 44 b is larger than the diameter (L1) of the first inner circumferential surface 44 a.

The coupling surface 44 c is located between the first inner circumferential surface 44 a and the second inner circumferential surface 44 b. The coupling surface 44 c is perpendicular to the axial direction Z and opposes the outer surface 11 d of the coupling wall 11 c in the axial direction Z. The outer surface 11 d of the coupling wall 11 c is one of opposite end surfaces of the housing 11 in the axial direction Z that corresponds to the coupling wall 11 c.

The cover 40 includes the flange 46 that projects sideward from an open end 41 b, which is the second end of the body 41. The flange 46 projects from the open end 41 b of the body 41 toward the radially outer side. The flange 46 opposes the outer surface 11 d of the coupling wall 11 c in the axial direction Z.

In the present embodiment, the fasteners 50 are bolts extending in the axial direction Z. The fasteners 50 fasten the flange 46 to the coupling wall 11 c. More specifically, the coupling wall 11 c includes fastening holes 51 (threaded holes) to which the fasteners 50 are fastened. The flange 46 includes communication holes 52 that are in communication with the fastening holes 51. The fasteners 50 are fastened to the fastening holes 51 through the communication holes 52.

In this case, the fasteners 50 press the flange 46 against the coupling wall 11 c. Thus, the flange 46 is in contact with the coupling wall 11 c. This limits the formation of a gap between the flange 46 and the coupling wall 11 c. In other words, the fasteners 50 fasten the flange 46 to the housing 11 with the flange 46 in contact with the housing 11.

In the present embodiment, the direction in which the fasteners 50 are fastened corresponds to the axial direction Z. The fastening direction of the fasteners 50 is the direction in which the flange 46 opposes the coupling wall 11 c, the direction in which the coupling wall 11 c opposes the bottom portion 42 of the body 41, and the direction orthogonal to the outer surface 11 d of the coupling wall 11 c.

Further, the flange 46 is in contact with the coupling wall 11 c. Thus, the cover 40 is connected to ground by the housing 11, and the cover 40 easily absorbs electromagnetic noise.

As shown in FIG. 2, the accommodation chamber S1 accommodating the heat-generating component 32 is defined by the body 41 of the cover 40 and the coupling wall 11 c of the housing 11. The accommodation chamber S1 is a space surrounded by the outer surface 11 d of the coupling wall 11 c, the inner surface 44 of the side portion 43 of the body 41, and the inner surface 42 a of the bottom portion 42 of the body 41.

The housing 11 includes a projection 60 projecting from the outer surface 11 d of the coupling wall 11 c toward the bottom portion 42 of the body 41. The projection 60 is formed from, for example, a thermally conductive metal in the same manner as the housing 11 and located in the accommodation chamber S1.

In the present embodiment, the projection 60 is annular (circular) as viewed in the axial direction Z. The projection 60 includes a side surface 61 (outer circumferential surface of projection 60) opposing the second inner circumferential surface 44 b in a direction intersecting (i.e., orthogonal to) the axial direction Z. Further, the projection 60 includes a distal end surface 62 having the form of a ring as viewed in the axial direction Z. The side surface 61 and the second inner circumferential surface 44 b are concentric to each other, and the diameter of the side surface 61 (outer diameter of projection 60) is smaller than the diameter of the second inner circumferential surface 44 b (inner diameter of part of side portion 43 corresponding to second inner circumferential surface 44 b). Thus, the side surface 61 is located radially inward from the second inner circumferential surface 44 b. The side surface 61 opposes the second inner circumferential surface 44 b in a direction intersecting (i.e., orthogonal to) the fastening direction of the fasteners 50. The opposing direction of the side surface 61 and the second inner circumferential surface 44 b corresponds to the radial direction of the second inner circumferential surface 44 b of the side surface 61.

In the present embodiment, the diameter of the side surface 61 is larger than the diameter of the first inner circumferential surface 44 a (inner diameter of part of side portion 43 corresponding to first inner circumferential surface 44 a). Thus, the distal end surface 62 of the projection 60 partially overlaps the coupling surface 44 c as viewed in the axial direction Z. The projection length of the projection 60 is set to be smaller than the length of the second inner circumferential surface 44 b in the axial direction Z so that the distal end surface 62 is separated from the coupling surface 44 c.

The motor-driven compressor 10 includes a seal 63 located between the housing 11 and the cover 40.

The seal 63 is located between the second inner circumferential surface 44 b and the side surface 61. More specifically, the seal 63 is located in a seal receptacle S2 that is defined by the second inner circumferential surface 44 b, the side surface 61, and the outer surface 11 d of the coupling wall 11 c. Since the coupling surface 44 c is separated from the distal end surface 62, the seal receptacle S2 opens toward a side opposite to the outer surface 11 d of the coupling wall 11 c. In the present embodiment, the side surface 61 of the projection 60 corresponds to a “first opposing surface,” and the second inner circumferential surface 44 b corresponds to a “second opposing surface.” That is, the first opposing surface is part of the projection 60, and the second surface is the second inner circumferential surface 44 b.

The seal 63 is, for example, an O-ring having an annular shape (circular shape) as viewed in the axial direction Z. The thickness of the seal 63 in a natural state is set to be slightly greater than or equal to the opposing distance of the second inner circumferential surface 44 b and the side surface 61. The seal 63 is held between the second inner circumferential surface 44 b and the side surface 61 in the opposing direction of the second inner circumferential surface 44 b and the side surface 61 (i.e., direction orthogonal to fastening direction of fasteners 50). This restricts the entry of foreign matter through a gap between the housing 11 and the cover 40, more specifically, a gap between the flange 46 and the coupling wall 11 c. When the seal 63 is held between the second inner circumferential surface 44 b and the side surface 61, the seal 63 is flattened and extended in the fastening direction of the fasteners 50.

In this case, as described above, the seal receptacle S2 opens toward the side opposite to the outer surface 11 d of the coupling wall 11 c. This limits the application of force in the fastening direction of the fasteners 50 to the seal 63. That is, a larger amount of force in the direction orthogonal to the fastening direction is applied to the seal 63 than in the fastening direction.

It is preferred that the height (length in axial direction Z) of the seal 63 be set to, for example, less than or equal to the projection length of the projection 60 in a natural state (i.e., prior to deformation). However, the height of the seal 63 in a natural state may be slightly greater than the projection length of the projection 60 as long as the force applied when the seal 63 is held between the coupling surface 44 c and the outer surface 11 d of the coupling wall 11 c is smaller than the force in the direction orthogonal to the fastening direction or as long as the seal 63 is not held between the coupling surface 44 c and the outer surface 11 d of the coupling wall 11 c.

As shown in FIG. 2, the motor-driven compressor 10 includes a heat transfer member 70 to which heat of the heat-generating component 32 is transferred.

The heat transfer member 70 is formed from a thermally conductive material, for example, metal such as aluminum. The heat transfer member 70 includes a base 71, bosses 72, and posts 73. The bosses 72 and the posts 73 project from the base 71.

The bosses 72 extend in the axial direction Z. Each boss 72 includes a distal end surface that abuts against the circuit board 31. The heat transfer member 70 and the circuit board 31 are coupled to each other by bolts 74, which serve as fasteners, extending through the circuit board 31. This unitizes the circuit board 31, the heat-generating component 32 connected to the circuit board 31, and the heat transfer member 70.

The posts 73 extend in the axial direction Z. The posts 73 are located closer to the side portion 43 of the cover 40 than the bosses 72. That is, the posts 73 are located between the bosses 72 and the side portion 43 in the radial direction. Each post 73 includes a distal end surface 73 a that is in contact with the bottom portion 42 of the body 41. The fastening of the fasteners 50 presses the posts 73 from the bottom portion 42 of the body 41 in the axial direction Z (i.e., direction from bottom portion 42 toward outer surface 11 d of coupling wall 11 c), which is the fastening direction of the fasteners 50. Thus, the heat transfer member 70 is pressed against the coupling wall 11 c of the housing 11.

The base 71 has the form of, for example, a plate (circular plate). In the present embodiment, the base 71 is located at the inner side of the annular projection 60. The base 71 includes a first surface 71 a that is in contact with the heat-generating component 32 when the circuit board 31, the heat-generating component 32, and the heat transfer member 70 are unitized as described above. This transfers heat from the heat-generating component 32 to the heat transfer member 70.

Further, the base 71 includes a second surface 71 b, which is located at a side opposite to the first surface 71 a. The second surface 71 b is in contact with the outer surface 11 d of the coupling wall 11 c when the heat transfer member 70 is pressed against the coupling wall 11 c by the fasteners 50. A portion of the base 71 is located between the heat-generating component 32 and the coupling wall 11 c.

Dimensional errors in the height of the posts 73 and the depth (length in axial direction Z) of the body 41 may actually form a gap between the flange 46 and the coupling wall 11 c. Nevertheless, the flange 46 and the coupling wall 11 c are coupled by the fasteners 50. Thus, the flange 46 is in contact with the coupling wall 11 c at least around the fasteners 50. The bottom portion 42 of the body 41 slightly warps and presses the posts 73 against the housing 11.

The present embodiment has the advantages described below.

(1) The motor-driven compressor 10 is provided with the housing 11 including the suction port 11 a, the electric motor 13 accommodated in the housing 11, the inverter circuit 30 that drives the electric motor 13, and the cover 40 that is arranged on the outer surface 11 d of the coupling wall 11 c and defines the accommodation chamber S1, which accommodates the inverter circuit 30, with the housing 11. The motor-driven compressor 10 includes the fasteners 50 that fasten the cover 40 to the housing 11.

In such a structure, the motor-driven compressor 10 includes the heat transfer member 70 to which heat of the heat-generating component 32, which forms the inverter circuit 30, is transferred. The fastening of the fasteners 50 presses the heat transfer member 70 in the axial direction Z, which is the fastening direction of the fasteners 50, against the housing 11. The housing 11 includes the side surface 61, and the cover 40 includes the second inner circumferential surface 44 b. The side surface 61 and the second inner circumferential surface 44 b oppose each other in the direction intersecting (i.e., orthogonal to) the fastening direction of the fasteners 50. Further, the motor-driven compressor 10 includes the seal 63 located between the side surface 61 and the second inner circumferential surface 44 b. The seal 63 is held between the side surface 61 and the second inner circumferential surface 44 b in the direction intersecting (orthogonal to) the axial direction Z.

In such a structure, the fastening of the fasteners 50 presses the heat transfer member 70 against the housing 11. This limits the formation of a gap between the heat transfer member 70 and the housing 11 so that heat exchange occurs between the heat transfer member 70 and the housing 11 in a preferred manner. Thus, the heat transfer member 70 transfers the heat of the heat-generating component 32 to the housing 11 in a preferred manner. This allows the heat of the heat-generating component 32 to be transferred through the housing 11 to refrigerant and thus cools the heat-generating component 32 in a preferred manner.

Further, the seal 63 is held between the side surface 61 and the second inner circumferential surface 44 b in the direction intersecting the axial direction Z. This limits the application of fastening force of the fasteners 50 to the seal 63 as compared to a structure in which the seal 63 is held in the fastening direction of the fasteners 50. Thus, deterioration of the seal 63 that would be caused when the fastening force of the fasteners 50 is continuously applied to the seal 63 is limited. The fasteners 50 that press the heat transfer member 70 against the housing 11 increases the efficiency for cooling the heat-generating component 32 and limits the deterioration of the seal 63 that would be caused by the fastening with the fasteners 50.

(2) The cover 40 includes the tubular body 41 and the flange 46. The body 41 includes the side portion 43 (circumferential wall) including the first end and the second end, which is located at the side opposite to the first end, and the bottom portion 42 (end wall) arranged at the first end. The flange 46 projects outward (toward radially outer side) from the open end 41 b (second end) of the side portion 43. The fasteners 50 fasten the flange 46 to the housing 11 with the flange 46 in contact with the coupling wall 11 c of the housing 11. The heat-generating component 32 is located in the accommodation chamber S1, which is defined by the metal housing 11 and the body 41. The seal 63 is located between the second inner circumferential surface 44 b, which is part of the inner surface 44 of the body 41, and the side surface 61.

In such a structure, electromagnetic noise generated at the heat-generating component 32 is absorbed by the housing 11 and the body 41 that define the accommodation chamber S1. This limits electromagnetic noise generated at the heat-generating component 32 that leaks out of the accommodation chamber S1.

In particular, the metal housing 11 and the body 41 define the accommodation chamber S1, and the non-metal seal 63 does not function as a member that defines the accommodation chamber S1. This limits electromagnetic noise that leaks through the seal 63 out of the accommodation chamber S1.

Further, the fasteners 50 fasten the flange 46 to the coupling wall 11 c of the housing 11. Thus, the formation of a gap between the flange 46 and the coupling wall 11 c is limited. This avoids problems that may occur when electromagnetic noise leaks through a gap resulting from dimensional errors or the like.

(3) The heat transfer member 70 includes the base 71, which is located between the heat-generating component 32 and the housing 11, and the posts 73, which extend from the base 71 toward the bottom portion 42 of the body 41 and contact the bottom portion 42 of the body 41. When the fasteners 50 are fastened, the bottom portion 42 of the body 41 presses the posts 73. This, in turn, presses the heat transfer member 70 against the housing 11. With this structure, the heat-generating component 32 is not directly pressed against the housing 11. This limits the application of excessive force to the heat-generating component 32.

In particular, in a structure in which the heat-generating component 32 is directly pressed against the housing 11 by the circuit board 31 or the like, excessive force would be applied to the heat-generating component 32. This may, for example, bend the terminals 32 a. In this regard, the present embodiment has a structure in which the heat transfer member 70 receives the fastening force of the fasteners 50. This limits the bending of the terminals 32 a.

(4) The inverter circuit 30 includes the circuit board 31, to which the heat-generating component 32 is connected. The heat transfer member 70, the heat-generating component 32, and the circuit board 31 are unitized with the heat-generating component 32 in contact with the heat transfer member 70. Such a structure limits separation of the heat transfer member 70 and the heat-generating component 32 that would be caused by displacement of the heat transfer member 70 and the heat-generating component 32 and allows heat to be exchanged between the heat-generating component 32 and the heat transfer member 70 in a preferred manner.

(5) The inner surface 44 of the housing 11 includes the first inner circumferential surface 44 a located at the side corresponding to the bottom portion 42, the second inner circumferential surface 44 b located at the side corresponding to the housing 11, and the coupling surface 44 c that couples the first inner circumferential surface 44 a and the second inner circumferential surface 44 b. The straight line L1 that extends through the center M of the first inner circumferential surface 44 a and connects two points on the first inner circumferential surface 44 a is shorter than the straight line L2 that extends through the center M of the second inner circumferential surface 44 b and connects two points on the second inner circumferential surface 44 b. The housing 11 includes the projection 60 projecting from the outer surface 11 d, which is the outer surface of the housing 11, of the coupling wall 11 c toward the bottom portion 42 of the body 41. The second inner circumferential surface 44 b and the side surface 61 of the projection 60 oppose each other in the direction intersecting the fastening direction of the fasteners 50. The seal 63 is located in the seal receptacle S2, which is defined by the outer surface 11 d of the coupling wall 11 c, the second inner circumferential surface 44 b, and the side surface 61. The coupling surface 44 c is located farther from the outer surface 11 d of the coupling wall 11 c than the distal end surface 62 of the projection 60. Thus, the seal receptacle S2 opens toward the side opposite to the outer surface 11 d of the coupling wall 11 c. In such a structure, when the seal 63 is flattened between the second inner circumferential surface 44 b and the side surface 61, a portion of the seal 63 is extended toward the coupling surface 44 c. Thus, the seal 63 is not held strongly pressed between the coupling surface 44 c and the outer surface 11 d of the coupling wall 11 c. This limits the application of force in the opposing direction of the coupling surface 44 c and the outer surface 11 d of the coupling wall 11 c (i.e., fastening force of fasteners 50) to the seal 63.

Second Embodiment

The structures of fasteners and a heat transfer member of a second embodiment differ from those of the first embodiment. The differences will be described below. In the second embodiment, like or same reference numerals are given to those components that are the same as the corresponding components of the first embodiment. Such components will not be described in detail.

As shown in FIG. 3, the second embodiment includes a disk-shaped projection 100. The projection 100 is not annular. The projection 100 includes a side surface 101 and a distal end surface 102. The side surface 101 corresponds to the side surface 61 of the first embodiment and opposes the radially inward part of the second inner circumferential surface 44 b. The distal end surface 102 of the second embodiment is circular as viewed in the axial direction Z. The projection 100 is, for example, formed from a thermally conductive metal in the same manner as the housing 11.

The second embodiment includes a heat transfer member 110 that is formed from a metal in the same manner as the heat transfer member 70 of the first embodiment. The heat transfer member 110 includes a base 111, bosses 112, posts 113, and through holes 114 extending through the base 111 and the posts 113.

The base 111 is disk-shaped and larger than the projection 100. The diameter of the base 111 is set to be larger than the diameter of the first inner circumferential surface 44 a (inner diameter of part of side portion 43 corresponding to first inner circumferential surface 44 a) and the diameter of the projection 100. In detail, the diameter of the base 111 is set to be slightly less than or equal to the second inner circumferential surface 44 b (inner diameter of part of side portion 43 corresponding to second inner circumferential surface 44 b). More specifically, a straight line L10 that extends through the center M of the base 111 and connects two points on the outer circumference of the base 111 is longer than the straight line L1 that extends through the center M of the first inner circumferential surface 44 a and connects two points on the outer circumference of the first inner circumferential surface 44 a and a straight line L3 that extends through the center M of the projection 100 and connects two points on the outer circumference of the projection 100. Further, the straight line L10 that extends through the center M of the base 111 and connects two points on the outer circumference of the base 111 is slightly shorter than or equal to the straight line L2 that extends through the center M of the second inner circumferential surface 44 b and connects two points on the outer circumference of the second inner circumferential surface 44 b.

The base 111 includes an overhang 111 a extending sideward from the projection 100 as viewed in the axial direction Z. The overhang 111 a abuts against the coupling surface 44 c and the second inner circumferential surface 44 b.

The bosses 112 and the posts 113 project from a first surface 111 b, which is the surface of the base 111 opposing the bottom portion 42 of the body 41. The bosses 112 correspond to the bosses 72 of the first embodiment. The posts 113 correspond to the posts 73 of the first embodiment except in that the posts 113 include the through holes 114.

The second embodiment includes fasteners 120. The fasteners 120 extend through the bottom portion 42 of the body 41, instead of the flange 46, and the posts 113 and the base 111 of the heat transfer member 110 to fasten the cover 40 to the housing 11.

More specifically, the bottom portion 42 of the body 41 includes communication holes 121 that are in communication with the through holes 114 of the heat transfer member 110. The projection 100 of the housing 11 includes fastening holes 122 (threaded holes) that are in communication with the through holes 114 of the heat transfer member 110. The fasteners 120, which are bolts, are extended through the communication holes 121 of the body 41 and the through holes 114 of the heat transfer member 110 and fastened to the fastening holes 122. Thus, the fastening of the fasteners 120 presses the heat transfer member 110 from the bottom portion 42 of the body 41 against the housing 11 (i.e., distal end surface 102 of projection 100). In this state, a second surface 111 c of the base 111, excluding the overhang 111 a, contacts the distal end surface 102 of the projection 100. That is, the base 111 of the second embodiment is held between the distal end surface 102 of the projection 100 and the coupling surface 44 c.

In such a state, the projection 100 of the housing 11, the body 41, and the seal 63 define an accommodation chamber S10 accommodating the inverter circuit 30. Further, the base 111 and the body 41 define a metal-surrounded chamber S11, which is surrounded by metal. The metal-surrounded chamber S11 is defined by the inner surface 42 a of the bottom portion 42, the first inner circumferential surface 44 a, and the first surface 111 b of the base 111. The inverter circuit 30 including noise sources such as the circuit board 31 and the heat-generating component 32 is located in the metal-surrounded chamber S11. That is, the seal 63 of the second embodiment functions as a member that defines the accommodation chamber S10 and does not function as a member that defines the metal-surrounded chamber S11.

The second embodiment includes a seal receptacle S12 defined by the second inner circumferential surface 44 b, the side surface 101, the outer surface 11 d of the coupling wall 11 c, and a portion of the second surface 111 c of the base 111 that corresponds to the overhang 111 a. The metal-surrounded chamber S11 and the seal chamber S12 are partitioned by the overhang 111 a. That is, the seal receptacle S12 is located outside the metal-surrounded chamber S11. The seal 63 is located in the seal receptacle S12.

The seal 63 is separated from at least one (both in the second embodiment) of the overhang 111 a and the outer surface 11 d of the coupling wall 11 c so that force in a fastening direction of the fasteners 120 is not applied to the seal 63.

However, the seal 63 may be in contact with both of the overhang 111 a and the outer surface 11 d of the coupling wall 11 c. In this case, the holding force of the side surface 101 of the projection 100 and the second inner circumferential surface 44 b and the fastening force of the fasteners 120 may be applied to the seal 63. In such a structure, the length of the seal receptacle S12 in the axial direction Z is obtained so that the fastening force of the fasteners 120 is sufficiently smaller than the holding force. For example, the seal receptacle S12 in the axial direction Z may be longer than the height of the seal 63 in a natural state (prior to deformation).

In the structure like the second embodiment in which the fasteners 120 fasten the bottom portion 42 of the body 41 and the coupling surface 44 c is in contact with the overhang 111 a, a gap may be formed between the flange 46 and the outer surface 11 d of the coupling wall 11 c because of dimensional errors. In such a case, the inverter circuit 30 is surrounded by the metal base 111 and the body 41. This limits electromagnetic noise of the inverter circuit 30 that leaks out of the metal-surrounded chamber S11 (i.e., accommodation chamber S10). Further, the seal 63 located in the seal receptacle S12 limits the entry of foreign matter or the like into the accommodation chamber S10 through the gap.

The cover 40 is electrically connected to the projection 100 of the housing 11 by the metal heat transfer member 110. Thus, the cover 40 is connected to ground by the heat transfer member 110 and the housing 11. This allows the cover 40 to easily absorb electromagnetic noise.

In the second embodiment, when the fasteners 120 are removed from the fastening holes 122, the inverter circuit 30 is removed from the housing 11 together with the cover 40 and the heat transfer member 110. This allows the inverter circuit 30 to be replaced relatively easily.

The second embodiment has the advantages described below.

(6) The motor-driven compressor 10 includes the heat transfer member 110, which includes the base 111 held between the distal end surface 102 of the projection 100 and the coupling surface 44 c of the body 41. The inverter circuit 30 is surrounded by the first inner circumferential surface 44 a, the bottom portion 42 (i.e., inner surface 42 a of bottom portion 42) of the body 41 and the base 111 (i.e., first surface 111 b) of the heat transfer member 110. In other words, the inverter circuit 30 is located in the metal-surrounded chamber S11 defined by the metal body 41 and the base 111 of the heat transfer member 110. The seal 63 is located between the side surface 101 of the projection 100 and the second inner circumferential surface 44 b, which are located outside the metal-surrounded chamber S11. In such a structure, the inverter circuit 30, which is surrounded by metal, limits electromagnetic noise, which is generated by the inverter circuit 30, out of the accommodation chamber S10. Further, the seal 63 is located outside the metal-surrounded chamber S11. Thus, the seal 63 limits the leakage of electromagnetic noise while sealing the gap between the housing 11 and the cover 40.

(7) The fasteners 120 extend through the bottom portion 42, the posts 113, and the base 111 and fasten the cover 40 to the housing 11. Thus, the fastening of the fasteners 120 further directly presses the posts 113 against the housing 11. That is, the fastening force of the fasteners 120 is further directly transmitted to the heat transfer member 110. This presses the heat transfer member 110 against the housing 11 so that the heat transfer member 110 comes into further secure contact with the housing 11.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms.

The heat transfer members 70 and 110 may be omitted. For example, as shown in FIG. 4, the cover 40 includes bosses 130 extending from the bottom portion 42 (i.e., inner surface 42 a of bottom portion 42) of the body 41 toward the housing 11 (i.e., outer surface 11 d of coupling wall 11 c). The bolts 74 are extended through the circuit board 31 and fastened to the bosses 130 to unitize the circuit board 31 and the cover 40. Further, when the heat-generating component 32 connected to the circuit board 31 is in direct contact with the outer surface 11 d of the coupling wall 11 c, the fasteners 50 fasten the cover 40 to the housing 11.

With such a structure, when fastened by the fasteners 50, the circuit board 31 is pressed against the outer surface 11 d of the coupling wall 11 c by the bosses 130. Thus, the heat-generating component 32 is pressed against the housing 11. This limits the formation of a gap between the heat-generating component 32 and the housing 11 and directly transfers the heat of the heat-generating component 32 to the housing 11. It is only necessary that the heat-generating component or the heat transfer member be pressed against the housing 11.

Nevertheless, it is preferred that the heat transfer member be pressed against the housing 11 to limit, for example, bending of the terminals 32 a that would be caused when the heat-generating component 32 is directly pressed against the housing 11.

The bases 71 and 111 may be pressed against the housing 11 with a heat transfer sheet or thermally conductive grease arranged between the base 71 and the housing 11 or between the base 111 and the housing 11. In addition, in the structure that presses the heat-generating component 32 toward the housing 11 like in the above modified example, the heat-generating component 32 may be pressed against the housing 11 with a heat transfer sheet or thermally conductive grease arranged between the heat-generating component 32 and the housing 11.

The fastening direction of the fasteners 50 and 120 correspond to the axial direction Z. However, the fastening direction of the fasteners 50 and 120 may slightly intersect the axial direction Z.

The motor-driven compressor may be of a camelback type in which the cover 40 is coupled to the side portion (circumferential wall) of the housing 11. In this case, the fastening direction of the fasteners 50 and 120 may be orthogonal to the axial direction Z. Even in such a structure, the housing 11 and the cover 40 respectively include a first opposing surface and a second opposing surface, the first opposing surface and the second opposing surface oppose each other in the direction intersecting (preferably, orthogonal to) the fastening direction of the fasteners 50 and 120, and a seal is arranged between the first opposing surface and the second opposing surface.

The opposing direction of the side surfaces 61 and 101 and the second inner circumferential surface 44 b is orthogonal to the fastening direction of the fasteners 50 and 120. However, the opposing direction of the side surfaces 61 and 101 and the second inner circumferential surface 44 b only needs to intersect the fastening direction of the fasteners 50 and 120. Even in this case, as compared to a structure in which the opposing direction corresponds to the fastening direction of the fasteners 50 and 120, the fastening force applied to the seal 63 is limited.

The flange 46 may be omitted. In this case, the outer surface 11 d of the coupling wall 11 c may include a recess to which the cover is fitted. In such a structure, the seal 63 is located between a side wall surface of the recess and an outer circumferential surface of the side portion that oppose each other. In this example, the side wall surface of the recess corresponds to the “first opposing surface,” and the outer circumferential surface of the side portion of the cover corresponds to the “second opposing surface.” That is, the first opposing surface may be located at the outer or inner side of the second opposing surface.

The seal 63 may form part of a partition that defines the accommodation chamber S1.

As long as heat of the heat-generating component 32 is transferred to the bases 71 and 111, a gap may be formed between the heat-generating component 32 and the bases 71 and 111.

The heat transfer member may have any specific shape. For example, there may be any number of the bosses 72 and 112 and the posts 73 and 113. In addition, the bases 71 and 111 may include recesses or through holes that accommodate the heat-generating component 32.

The coupling surface 44 c of the cover 40 may be in contact with the distal end surfaces 62 and 102 of the projections 60 and 100. In addition, the coupling surface 44 c may be omitted.

There may be one or more heat-generating components 32.

The motor-driven compressor 10 does not have to be used with the on-vehicle air conditioner 200. For example, when a fuel cell is installed in the vehicle, the motor-driven compressor 10 may be used with an air supply device that supplies the fuel cell with air. That is, the fluid that is compressed is not limited to refrigerant and may be, for example, air.

The fluid machine is not limited to the motor-driven compressor 10. For example, when a fuel cell is installed in the vehicle, the fluid machine may be an electric pump device that supplies the fuel cell with hydrogen. In this case, the electric pump device includes a pump, which supplies hydrogen of a hydrogen tank without compressing the hydrogen, and an electric motor, which drives the pump.

The motor-driven compressor 10 does not have to be installed in a vehicle.

Each of the embodiments may be combined with each of the modified examples. For example, in the second embodiment, the fasteners 120 may be fastened to the housing 11 at a portion of the flange 46 instead of the bottom portion 42 of the body 41. In this case, the posts 113 may be omitted. Further, even in this case, the heat transfer member 110 is pressed against the distal end surface 102 of the projection 100 by the coupling surface 44 c. In addition, the cover 40 may be fastened to the housing 11 at portions of the bottom portion 42 of the body 41 and the flange 46. This increases force that presses the heat transfer member 110 toward the housing 11.

Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims. 

1. A fluid machine comprising: a housing including a suction port through which fluid is drawn; an electric motor accommodated in the housing; a drive circuit including a heat-generating component, wherein the drive circuit drives the electric motor; a cover arranged on an outer surface of the housing, wherein the cover defines an accommodation chamber, which accommodates the drive circuit, with the housing; a fastener that fastens the cover to the housing, wherein the cover is configured to press the heat-generating component or a heat transfer member, to which heat of the heat-generating component is transferred, against the housing in a fastening direction of the fastener when fastened by the fastener, and the housing includes a first opposing surface and the cover includes a second opposing surface that opposes the first opposing surface in a direction intersecting the fastening direction of the fastener; and a seal arranged between the first opposing surface and the second opposing surface, wherein the seal is held between the first opposing surface and the second opposing surface in the direction intersecting the fastening direction of the fastener.
 2. The fluid machine according to claim 1, wherein: the cover and the housing are formed from a metal: the cover includes a body including a circumferential wall and an end wall, wherein the circumferential wall includes a first end and a second end located at a side opposite to the first end, and the end wall is located at the first end of the circumferential wall, and a flange projecting outward from the second end; the fastener fastens the flange and the housing with the flange in contact with the housing, the heat-generating component is located in the accommodation chamber that is defined by the body and the housing, and the second opposing surface is part of an inner surface of the circumferential wall.
 3. The fluid machine according to claim 1, wherein the cover includes a body including a circumferential wall and an end wall, wherein the circumferential wall includes a first end and a second end located at a side opposite to the first end, and the end wall is located at the first end of the circumferential wall, the fluid machine includes the heat transfer member, the heat transfer member includes a base that is partially located between the heat-generating component and the housing, and a post that extends from the base toward the end wall and contacts the end wall, and when fastened by the fastener, the post is pressed by the end wall, which, in turn presses the heat transfer member against the housing.
 4. The fluid machine according to claim 3, wherein the cover is fastened to the housing with the fastener extending through the end wall, the post, and the base.
 5. The fluid machine according to claim 3, wherein the cover and the heat transfer member are formed from a metal, the circumferential wall includes an inner surface including a first inner circumferential surface located at a side corresponding to the first end, a second inner circumferential surface located at a side corresponding to the second end, and a coupling surface that couples the first inner circumferential surface and the second inner circumferential surface, a straight line that extends through a center of the first inner circumferential surface and connects two points on the first inner circumferential surface is shorter than a straight line that extends through a center of the second inner circumferential surface and connects two points on the second inner circumferential surface, the housing includes a projection projecting from the outer surface of the housing toward the end wall, wherein the projection includes a distal end surface that contacts the base, the second opposing surface is the second inner circumferential surface, the first opposing surface is part of the projection, and the base is held between the coupling surface and the distal end surface.
 6. The fluid machine according to claim 3, wherein the drive circuit includes a circuit board to which the heat-generating component is connected, and the heat transfer member, the heat-generating component, and the circuit board are unitized with the heat-generating component in contact with the heat transfer member.
 7. The fluid machine according to claim 3, wherein the cover and the heat transfer member are formed from a metal, the body includes an opening that opens toward the housing, wherein the opening is located at the second end, the circumferential wall includes an inner surface including a first inner circumferential surface located at a side corresponding to the first end, a second inner circumferential surface located at a side corresponding to the second end and having a larger diameter than the first inner circumferential surface, wherein the second inner circumferential surface forms the second opposing surface, and a step surface located between the first inner circumferential surface and the second inner circumferential surface, the housing includes a projection that projects from an end surface of the housing, wherein the projection includes a distal end surface that is in contact with the base, and the projection includes a side surface, which serves as the first opposing surface, located radially inward from the second inner circumferential surface, the base is held between the step surface and the distal end surface, and a metal-surrounded chamber surrounded by metal is defined by the first inner circumferential surface, the end surface, and the base, wherein the drive circuit is located in the metal-surrounded chamber, and the seal is located outside the metal-surrounded chamber.
 8. The fluid machine according to claim 1, wherein the fluid machine is a motor-driven compressor including a compression unit that compresses fluid drawn from the suction port when the electric motor is driven. 